Surface Modification of Wood Using Nitric Acid

Surface modification of wood flakes by oxidation with nitric acid has been investigated at three different moisture contents of wood, and two different concentrations of the oxidant. It is shown that a significant number of the acid groups generated are chemically linked to wood. Increasing moisture content in wood has the effect of local dilution of the nitric acid oxidant while reduction in moisture content of wood during drying makes potential oxidation sites less accessible. Thus, two different regimes of oxidation, one of more accessible, and another, of less accessible, sites are observed. The nature of the generated acid is established as carboxylic, which is capable of undergoing a coupling reaction with 2-(l-aziridinyl)ethyl methacrylate. The catalysis of in situ polymerization of furfuryl alcohol by bound acid has also been shown to occur.